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Small scale DAB trial coverage maps

26 September 2016

The maps below provide an indication of the coverage that the small scale DAB trial multiplexes are expected to achieve based on their current operating parameters and subject to the constraints set out below. This is not a guarantee of coverage for trial licensees, nor does it indicate the likely coverage of small-scale DAB multiplexes under any longer-term licensing framework.

These maps do not take account of adjacent channel interference which may prevent reception of the small scale service near to any other radio service's DAB transmitter site from which the small scale DAB service does not radiate.

These maps represent the percentage of locations served rather than the specific field strength level predicted at a point, as depicted on Ofcom AM and FM coverage maps. The percentage of locations served is a measure of how many random points the receiver is expected to work at in a 100m square area (the size of a prediction pixel). For example, if we state that 95% of locations should be served the radio should work at 95 out of every 100 randomly chosen places within the prediction pixel.

One map is supplied for each service which shows the following levels of coverage:

Mobile coverage in yellow (based on 99% location availability).

Indoor coverage in green (based on 80% location availability).

Mobile coverage indicates locations where car and portable radios used outdoors are predicted to receive a signal. A high percentage location availability is deemed necessary in order to minimise the possibility that a stationary vehicle (e.g. at traffic lights or road works), might be in an unserved location. Consequently when vehicles are in motion reception may well be possible beyond the areas shown.

Indoor coverage indicates where a radio with an indoor aerial is likely to receive a signal. This measure takes account of expected losses as the signal passes through the walls of typical buildings. In the case of indoor coverage we consider that 80% locations provides a usable service. We do not believe that coverage at 99% locations is necessary indoors as the listener has the opportunity to place the radio at a number of positions.

Ofcom DAB coverage maps are produced using the BBC software implementation of the UK planning model (UKPM). The UKPM methodology has been agreed between Ofcom, Arqiva, and the BBC. However, the actual implementation of the UKPM processes does vary between the organisations due to factors such as operating platform and program coding. As a result predictions and coverage figures produced for the same set of wanted and interfering transmitter parameters by different organisations can be expected to exhibit small variations.

Predicted population figures for the ten trial multiplexes are provided below. These are based on the indoor coverage standard described above (80% locations at 1% time interference, using the proportional population counting method described here (PDF, 235.1 KB).

The coverage indicated does not represent or imply any warranty by Ofcom that the technical conditions which form the basis of its definition are satisfied at all points within the area shown, nor that these conditions would not be satisfied at locations outside of that area. The associated technical conditions represent a conservative average threshold (for each relevant measure) for generally acceptable reception for most circumstances. Because of factors such as the variation in sensitivity of individual models of receiver, some listeners find these thresholds too low to deliver what they would like, and others enjoy what they regard as adequate reception under 'worse' conditions than those corresponding to these thresholds. Reception quality can also differ rapidly with changes in location, to a more detailed extent than is shown on the map.